PROJECT SUMMARY/ABSTRACT The proposed project will prepare the applicant for an impactful independent research career studying the etiology and prevention of substance use disorder (SUD), particularly in relation to trauma and posttraumatic stress disorder (PTSD). To achieve this career goal, the project targets predoctoral training in four key areas over a 2-year award period: preventative intervention development and evaluation, SUD etiology and risk conferred by trauma-related pathology, knowledge and assessment of trauma-related biological processes in SUD (i.e., sleep and stress responding), and professional development. This training will be conducted under the mentorship of experts in each of these specific areas. The proposed research training plan is the ideal avenue for the applicant to gain these essential skills. Specifically, the proposed project addresses the critical need for targeted direct SUD prevention among trauma survivors by integrating empirical observations that 1) sleep disturbance is a risk factor for SUD, common among trauma survivors, and 2) sleep disturbance is malleable and potentially more amenable to change compared to directly targeting substance use, as well as 3) theoretical conceptualizations of the role of sleep in promoting key risk factors for SUD: stress, cravings and substance use to decrease negative affect. Building on this work, the current proposal will test the effects of Brief Behavioral Treatment for Insomnia (BBTI) compared to a waitlist control on SUD risk reduction. A further aim is to investigate biobehavioral mechanisms underlying improving sleep to ameliorate SUD risk (i.e., stress reactivity, associated cravings, substance use to relieve negative affect). Cannabis use was selected due to its close connection with sleep disturbance and its widespread use. To examine these aims, a sample of 60 young adults (aged 18-30) with poor sleep at risk for SUD (i.e., use cannabis at least once weekly and trauma exposed with or without PTSD) will be recruited. Participants will complete a baseline assessment including self-report, clinical interviewing, a behavioral task, and hormonal assays, then will be randomized into condition, complete their assigned intervention, and participate in follow-ups over a 3-month period. Hypotheses are: 1) BBTI will reduce SUD risk (i.e., fewer cannabis use disorder [CUD] symptoms and diagnoses, decreased coping motives, use-related problems, and PTSS) at follow-up, compared to a waitlist control; 2) that the effect of condition on SUD risk reduction will be mediated by improvements in sleep; 3) that BBTI will have high levels of treatment satisfaction in this vulnerable group; 4) that poor sleep will be associated with, and BBTI will improve: increased negative affect, cortisol secretion, and cravings following trauma imagery. The long-term goals of this research are to inform theoretical models of the development of SUD, and to guide future preventative intervention research. These goals have significant public health importance, considering the crucial need to reduce the substantial public health burden associated with SUD.